refactor(cli): split doctor/model-resolution and run/events into focused modules

Doctor checks:
- model-resolution-cache.ts, model-resolution-config.ts
- model-resolution-details.ts, model-resolution-effective-model.ts
- model-resolution-types.ts, model-resolution-variant.ts

Run events:
- event-formatting.ts, event-handlers.ts
- event-state.ts, event-stream-processor.ts

src/cli/doctor/checks/model-resolution-cache.ts

@@ -0,0 +1,36 @@
+import { existsSync, readFileSync } from "node:fs"
+import { homedir } from "node:os"
+import { join } from "node:path"
+import type { AvailableModelsInfo } from "./model-resolution-types"
+
+function getOpenCodeCacheDir(): string {
+  const xdgCache = process.env.XDG_CACHE_HOME
+  if (xdgCache) return join(xdgCache, "opencode")
+  return join(homedir(), ".cache", "opencode")
+}
+
+export function loadAvailableModelsFromCache(): AvailableModelsInfo {
+  const cacheFile = join(getOpenCodeCacheDir(), "models.json")
+
+  if (!existsSync(cacheFile)) {
+    return { providers: [], modelCount: 0, cacheExists: false }
+  }
+
+  try {
+    const content = readFileSync(cacheFile, "utf-8")
+    const data = JSON.parse(content) as Record<string, { models?: Record<string, unknown> }>
+
+    const providers = Object.keys(data)
+    let modelCount = 0
+    for (const providerId of providers) {
+      const models = data[providerId]?.models
+      if (models && typeof models === "object") {
+        modelCount += Object.keys(models).length
+      }
+    }
+
+    return { providers, modelCount, cacheExists: true }
+  } catch {
+    return { providers: [], modelCount: 0, cacheExists: false }
+  }
+}